[TUHS] First Unix that could run on a PDP-11 with QBUS

Warren Toomey wkt at tuhs.org
Tue Jul 29 19:46:48 AEST 2014

The old AUUG newsletters are all at http://minnie.tuhs.org/Archive/Documentation/AUUGN/

Cheers, Warren

On 29 July 2014 08:23:12 AEST, Dave Horsfall <dave at horsfall.org> wrote:
>On Mon, 28 Jul 2014, Noel Chiappa wrote:
>> > I recall that there were other differences as well, but only minor.
>> > my paper in AUUGN titled "Unix on the LSI-11/23" it will reveal all
>> > about porting V6 to the thing.
>> I did a google for that, but couldn't find it. Is it available
>> online? (I'd love to read it.) I seem to recall vaguely that AUUGN
>> were online, but if so, I'm not sure why the search didn't turn it
>There was a project a few years ago to scan all issues of AUUGN 
>(Australian Unix Users Group Newsletter); the last I heard was that all
>issues had been obtained, and handed over to some Google mob for 
>archiving.  Apparently the scanning process is destructive but makes
>an ideal copy for as many as you like.  The originals, being up to 40 
>years or so old, would have been in bad shape anyway.
>A search for "auugn" reveals a few pointers, but AUUG itself dissolved
>few years ago because we had achieved our purpose i.e. bring Unix to
>mass market in Australia (its competition at the time was RSTS, RSX,
>PICK of all things).  Guess which one survived?  Concurrent CP/M never 
>really had a hold, MS-DOS thankfully died (I was still using CP/M at
>time; heck, I even had UUCP on it, which was pretty impressive
>that the Microbee didn't have a serial port), and I predict that
>will go the way of the Irish potato crop and for the same reason.
>Warren may know more about the archived issues.
>> > I vaguely remember that the LTC had to be disabled during the boot 
>> > process, for example, with an external switch.
>> I think you might be right, which means the simulated 11/23 I tested
>> wasn't quite right - but keep reading!
>It was hilarious, in a morbid sort of way.  I cottoned on when the 
>bootstrap process crapped itself for no apparent reason (it got 
>interrupted when no ISR was in place), and we'd occasionally forget to 
>enable it...
>> I remember being worried about this when I started doing the V6 11/23
>> version a couple of months back, because I remembered the 11/03's
>> have a programmable clock, just a switch. So I was reading through
>> 11/23 documentation (I had used 11/23s, but on this point my memory
>> faded), trying to see if they too did not have a programmable clock.
>> As best I can currently make out, the answer is 'yes/no, depending on
>> the exact model'! E.g. the 11/23-PLUS _does_ seem to have a
>> clock (see pg. 610 of the 1982 edition of "microcomputers and 
>> memories"), but the base 11/23 _apparently_ does not.
>I never saw the -PLUS, so I can't help you there, and my shelf of DEC
>Unix etc manuals disappeared during several moves.
>> Anyway, the simulated 11/23 (on Ersatz11) does have the LTC (I just 
>> checked, and 'lks' contains '0177546', so it thinks it has one :-).
>Quite likely.  I came up with a battery of tests at boot time, in order
>determine just what sort of a model it was e.g. did it have the SLR and
>on.  Same thing for illegal instructions, such as floating point.  We
>/40s all over the place (some dedicated ones had no MMU, and ran a
>program to talk 200-UT to a remote Cyber), two or three /70s (I had no 
>responsibility for those, but we shared code a lot), a /60 (interesting
>box), and a sprinkling of /23s.
>> But this will be easy to code around; if no link clock is found (in 
>> main.c), I'd probably set 'lks' to point somewhere harmless (054, say
>> I'm using 050/052 to hold the pointer to the CSW, and the software
>> if there isn't a hardware one). That way I can limit the changes to
>> in main.c, I won't have to futz with clock.c too.
>Speaking of the CSW, we came up with some amusing idle patterns.  The 
>boxes with the octal display displayed rotating 1s (I had to determine 
>whether it had an octal display or a real one somehow; I've long since 
>> PS: On at least the 11/40 (and maybe the /45 too), the line clock was
>> option! It was a single-height card, IIRC.
>Yeah; the aforementioned low-end /40s had quite an impressive program
>scheduled by the use of co-routines (no LTC either).  It emulated the
>Remote Batch Station (we briefly had one of those too; it was S L O W).
>Fun days!
>-- Dave
>TUHS mailing list
>TUHS at minnie.tuhs.org

Sent from my Android phone with K-9 Mail. Please excuse my brevity.
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